USMLE USMLE-STEP-2 Online Practice Questions and Exam Preparation

USMLE USMLE-STEP-2 Online Questions & Answers

• Question 341:

  An obese 21-year-old woman complains of increased growth of coarse hair on her lip, chin, chest, and abdomen. She also notes menstrual irregularity with periods of amenorrhea. Which of the following is the most likely cause of this patient's symptoms?

  A. polycystic ovary disease
  B. an ovarian tumor
  C. an adrenal tumor
  D. Cushing disease
  E. familial hirsutism
  A. polycystic ovary disease

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  Explanation

  As many as 85% of women with hirsutism, obesity, and menstrual irregularities have polycystic ovary disease (Stein-Leventhal syndrome). Women with this disorder have chronic anovulation and frequent infertility despite the presence of adequate amounts of estrogen. Excessive luteinizing hormone (LH) response to gonadotropin-releasing hormone is thought by many to be the primary problem, resulting in ovarian theca-cell hyperplasia and hypersecretion of androgens. Others have found deficiencies of the ovarian enzymes involved in estrogen biosynthesis. Diagnosis is based on an elevated LH level, decreased follicle-stimulating hormone (FSH) level, and an LH/FSH ratio greater than 2:5. Combination estrogen- progestin therapy suppresses the androgen production. Less common causes of hirsutism are drug induced (e.g., testosterone, anabolic steroids), adrenal tumor or hyperplasia, Cushing disease, and ovarian tumors. Familial hirsutism is not associated with menstrual abnormalities or obesity.

• Question 342:

  Narcolepsy is a primary sleep disorder with all of the following symptoms except which of the following?

  A. sleep paralysis
  B. sleep attacks with sleep onset REM (rapid eye movement)
  C. cataplexy
  D. hypnagogic hallucinations
  E. apnea
  E. apnea

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  Explanation

  Narcolepsy is a rare dyssomnia (incidence of .07%) defined by the following four symptoms: sleep paralysis occurs upon falling asleep or waking, sleep attacks with sleep onset REM which are brief (1015 minutes) and occur in inappropriate situations (sleep attacks are effectively treated with stimulants), cataplexy which is a condition that involves sudden transient bilateral weakness or paralysis, and hypnagogic hallucinations. Apnea is the cessation of nasobuccal breathing for more than 10 seconds and is found in obstructive sleep apnea, central sleep apnea, and mixed sleep apnea.

• Question 343:

  A 42-year-old man admitted with a high fever and leukocytosis is transferred to the intensive care unit in shock. Which of the following is a common finding in the early stages of septic shock?

  A. reduced cardiac output
  B. bradycardia
  C. decreased systemic vascular resistance (SVR)
  D. hypertension
  E. metabolic alkalosis
  C. decreased systemic vascular resistance (SVR)

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  Explanation

  The usual early hemodynamic response to sepsis is a hyperdynamic circulation. This includes tachycardia, elevated cardiac output, and decreased systemic resistance. Septic shock may then progress with intractable hypotension, metabolic acidosis, reduced cardiac output, oliguria, and death. The initial resuscitation of patients with all forms of shock requires rapid expansion of circulating blood volume to help maintain BP and tissue perfusion. This is usually achieved with the infusion of crystalloid fluids.

  When septic shock is suspected, cultures of blood, urine, and other sources along with antibiotic therapy targeted toward the most likely source is critical. Mechanical ventilation may be required when altered mental status, acidosis, and hypoxia are present. Beta-blockers and diuretics may have specific indications that cardiac ischemia and pulmonary edema are present

• Question 344:

  You are called to the ICU to see a 65-year-old female who is 2 days status post hip surgery. The medical team is concerned because the patient is having visual hallucinations and did not sleep last night. She scored 21/30 on a Mini-Mental Status Examination (MMSE) with 5 points off for disorientation and 2 off for both concentration and shortterm memory. The patient is restrained because she pulled out her IV last night. Records indicate she has no previous psychiatric history and that her cognitive functioning presurgery was normal.

  Which of the following is the most likely axis I diagnosis?

  A. bipolar disorder manic phase
  B. schizophrenia, undifferentiated
  C. dementia NOS (not otherwise specified)
  D. delirium NOS
  E. psychosis NOS
  D. delirium NOS

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  Explanation

  The hallmark of delirium is fluctuation in level of consciousness. Periods of lucency may be interspersed with periods of clouding and unresponsiveness. Impaired judgment, impaired memory, and disorientation are seen in both delirium and dementia. Disordered thought is seen in both and tends to be disorganized in delirium and impoverished in dementia. Another distinguishing feature is that the onset of delirium usually occurs within hours or days, whereas, the onset of dementia may be insidious throughout a period of weeks to months.

• Question 345:

  For each item, select the ONE best lettered option that is most closely associated with it. Each lettered heading may be selected once, more than once, or not at all. A 45-year-old woman has noticed changes in the fat distribution on her body with excess fat over the posterior neck and upper back. On examination, she has high BP and abdominal striae. Laboratory evaluation shows a high glucose intolerance.

  A. Cushing's syndrome
  B. Addison's disease
  C. Klinefelter syndrome
  D. hyperparathyroidism
  E. hypothyroidism
  F. pheochromocytoma
  G. acromegaly
  H. diabetes insipidus
  I. diabetes mellitus
  J. polycystic ovarian disease
  A. Cushing's syndrome

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  Explanation

  Cushing's syndrome is caused by overproduction of cortisol by the adrenal gland. Centripetal obesity occurs in 97% of patients, increased body weight in 94%, fatigability and weakness in 87%, and hypertension in 82%. Impaired glucose tolerance is common and attributable to increased hepatic gluconeogenesis and insulin resistance.

• Question 346:

  A 78-year-old woman is seen by a psychiatrist for depression. She is fairly cooperative in responding to questions. She admits to feeling blue; she "catnaps" throughout the day and is up at night; and her appetite is very poor. She thinks of death frequently but denies feeling suicidal. There is no past psychiatric history. On the MMSE, she obtains a score of 14. Her depressive symptoms have been present for "several days." Which of the following is highly suggested by the findings?

  A. impaired cognitive functioning
  B. psychosis not otherwise specified
  C. bipolar disorder--manic
  D. dysthymia
  E. changes secondary to normal aging
  A. impaired cognitive functioning

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  Explanation

  One of the most significant findings here is that the woman, cooperative with the examination, has the score of 14 on the MMSE. Ascore of 2530 indicates no cognitive impairment, 2025 suggests possible mild impairment, and less than 20 is very strongly suggestive of cognitive impairment. This degree of change on the MMSE is not a normal sign of aging. In addition, there are no signs of psychosis or mania. Even if there were, in this woman with no previous sychiatric history, one would not likely consider

  psychosis not otherwise specified or mania. The time frame for dysthymia is not met by the "several days" length described here.

• Question 347:

  For each organism causing food-related illness, choose the corresponding average incubation period.

  What is the average incubation period of Staphylococcus aureus:

  A. under 4 hours
  B. 824 hours
  C. 1236 hours
  D. 12 hours to 6 days
  E. 13 weeks
  A. under 4 hours

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  Explanation

  Knowing the incubation period (average and range) of a pathogen can be important in determining the source of infection in food-borne disease. Knowing what food was eaten on the day of an attack of food poisoning may not help in establishing C. botulinum as the cause of illness, since certain strains of S. aureus cause food-borne disease by the production of enterotoxin. As no time is required after ingestion for the growth of colonies in the infected host, and the toxin affects the vagus nerve in the stomach, the incubation period is under 4 hours. C. perfringens, formerly known as Clostridium welchii, causes food- borne disease, after 824 hours when enterotoxin is released when C. perfringens passes from stomach to intestine. Meat prepared in bulk for consumption at a banquet or in an institution is a possible source. Spores that survive incomplete cooking may start reproducing during cooling and may persist if subsequent rewarming is not completed to a temperature above 60°C (140°F) required to kill the organisms. Salmonella has an incubation time of 1236 hours. It may also survive in meat and other products if cooking is inadequate and heat does not penetrate below the surface of the food. The organisms multiply in the gut of the infected host, and low infective doses may therefore have longer incubation periods

• Question 348:

  A group of male workers between the ages of 20 and 39 years are being screened for lung disease by spirometry. Nine subjects are examined. Their forced expiratory volume in 1 second (FEV1) divided by forced vital capacity (FEV1/ FVC %) results are 80, 76, 73, 61, 64, 79, 64, 64, and 78. What is the median value?

  A. 61
  B. 64
  C. 71
  D. 73
  E. 76
  D. 73

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  Explanation

  The median is the observation that lies in the middle of the series, if the observations are tabulated in numerical order. Half of the observations are lower in numerical value than the median, and the remainder are higher. Clearly, this value is easily identified if the series contains an odd number of readings. Although not very frequently used as a statistic, the median has the advantage of not being affected by extreme observations. For example, if the lowest reading of those in the question had been 55 instead of 61, the median would be unchanged.

• Question 349:

  A 4-year-old child presents with an enlarged submandibular node that is 4 cm in diameter, nontender, and not fluctuant. The node has been enlarged for about 4 weeks, and there is no history of fever or contact with any person who was ill. A CBC is normal, and a Mantoux test with 5 tuberculin units of PPD shows 6 mm of induration. Which of the following is the most likely diagnosis?

  A. cat-scratch fever
  B. acute pyogenic lymphadenitis
  C. acute lymphoblastic leukemia
  D. tuberculous lymphadenitis
  E. atypical mycobacteria lymphadenitis
  E. atypical mycobacteria lymphadenitis

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  Explanation

  Nontuberculous lymphadenitis (atypical mycobacteria) is characterized by nontender lymphadenitis. Affected persons are usually afebrile, and the CBC is usually normal. Unlike tuberculous lymphadenitis, a history of contact with a tuberculous individual is lacking, and the reaction to 5 tuberculin units of PPD is almost always less than 10 mm of induration. Cat-scratch fever is characterized by tender, fluctuating nodes and low-grade fever. Acute lymphadenitis is characterized by tender nodes that may fluctuate. The WBC count is often elevated, and there is frequently a shift to the left on the differential. In addition, the sufferer is often febrile. Acute lymphoblastic leukemia may present as lymphadenitis, but the CBC is usually abnormal, with blasts present on the peripheral smear

• Question 350:

  A15-month-old African American male, who is otherwise healthy, is found to have an emoglobin level of 8 g/dL on routine screening. The mean corpuscular volume (MCV) is decreased. His lead screen is within normal limits. You obtain a diet history, which reveals that he drinks about 3040 oz of whole cow's milk a day. He eats no meat and some fruits and vegetables.

  The most effective next step in management would be to obtain which of the following?

  A. iron studies--serum iron, total iron binding capacity, ferritin
  B. reticulocyte count
  C. hemoglobin electrophoresis
  D. a repeat hemoglobin in 1 month after treatment with folic acid
  E. a repeat hemoglobin in 1 month after treatment with iron
  E. a repeat hemoglobin in 1 month after treatment with iron

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  Explanation

  If iron deficiency is strongly suspected, it is reasonable to treat empirically with 36 mg/kg/day of elemental iron. An increase in hemoglobin of 1 g/dL within 24 weeks confirms the diagnosis. If laboratory confirmation is necessary because the child is at low risk for iron deficiency, confirmatory iron studies may be obtained. The serum iron is low, the total iron binding capacity high, and the ferritin is low. Areticulocyte count is helpful in hemolytic anemias where it is elevated. Bone marrow aspirate in iron deficiency is necessary if bone marrow infiltration is suspected (leukemia), but is overinvasive in this situation. Hemoglobin electrophoresis may be done if thalassemia or sickle cell anemia is likely.